Having a plugin on the server that has `AsyncCatcher.enabled = false;` in its onEnable causes the following exception to be thrown whenever a player joins the server:
```
[00:18:42] User Authenticator #2/INFO: Disconnecting illuminator3 (/127.0.0.1:64437): Failed to verify username!
[00:18:42] User Authenticator #2/WARN: Exception verifying illuminator3
java.lang.IllegalStateException: AsyncPlayerPreLoginEvent cannot be triggered asynchronously from primary server thread.
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:580) ~[spigot-api-1.21.5-R0.1-SNAPSHOT.jar:?]
        at net.minecraft.server.network.LoginListener.callPlayerPreLoginEvents(LoginListener.java:339) ~[spigot-1.21.5-R0.1-SNAPSHOT.jar:4495-Spigot-3dafb73-080f5dc]
        at net.minecraft.server.network.LoginListener$2.run(LoginListener.java:291) [spigot-1.21.5-R0.1-SNAPSHOT.jar:4495-Spigot-3dafb73-080f5dc]
[00:18:42] [Server thread/INFO]: illuminator3 (/127.0.0.1:64437) lost connection: Failed to verify username!
```